This is an excerpt from Le Viandier de Taillevent
(France, ca. 1380 - James Prescott, trans.)
The original source can be found at
James Prescott's website
Bright green soup of eels. Skin or scald them, and cook them in wine and water. Crush bread and parsley, with just a bit of saffron in the greens (to make it bright green), and soak in your broth. Crush ginger steeped in verjuice, and boil everything together. You can add good cheese cut into little cubes if you wish.